1. Field of the Invention:
The present invention relates generally to the field of automatic ball throwing apparatus and more particularly to automatic ball throwing apparatus having ball feeding mechanisms incorporated thereinto, and still more particularly to tennis ball feeding and throwing apparatus.
2. Discussion of the Background:
As is well known, a number of sports involve the hitting of thrown or otherwise projected balls. Notable among such sports are baseball and tennis, both of which require continual and diligent practice to improve a player's skill in hitting or returning the ball, to help a player increase his or her strength and, in many cases, to increase the player's stamina.
It might be presumed that the best type of training practice for players of sports involving the hitting or returning of a projected ball would be in an actual playing situation. For instance, it might be presumed that the best practice for a baseball batter would be to have another player pitching balls to him or her. Similarly, it might be presumed that the best practice for a tennis player would be for the player actually to play against a skilled tennis player. In many instances, such presumptions may be correct, since batting against a live pitcher or playing against a live tennis player involves actual and variable competitive conditions.
Nevertheless, such practice against live opponents is not always possible or practical and, moreover, is often not even the optimum practice. For example, unless the individual practicing is a star player for a professional team, it may simply be too expensive to provide full time access to a live training pitcher or expert tennis partner. Even if it were feasible cost-wise to have a full time practice partner, a practicing individual may often require a special amount of repeative practice with respect to a particular pitch or type of serve. As an illustration, a tennis player may need particular practice on his or her backhand stroke, or may need practice returning balls served or hit to particular areas of the tennis court, or may need practice in returning high or low balls. In such cases, a live pitcher or opponent may not be capable of consistantly providing the type of pitch or serve needed by the individual in training.
To overcome at least some of these problems, automatic ball pitching and throwing machines have been used for a number of years. These machines are virtually tireless and are generally fairly capable of providing at least somewhat consistantly thrown or served balls. To throw the balls, such machines typically employ either compressed air (especially for light balls like tennis balls) or one or a pair of rotatably driven ball-ejecting wheels. Because of their loud, air-blast noise, compressed air-type ball throwing machines are not particularly favored. Therefore, most ball throwing machines use a rotatably driven wheel or pair of wheels. Assuming, as an example, the use of a pair of rotatably driven wheels, the two wheels are spaced apart about the diameter of the ball to be projected thereby and are typically rotatably driven in opposite directions. Balls to be projected by the machine are fed into the gap between the wheels, are frictionally picked up by the wheels and are expelled at what are often high velocities. It is not uncommon for the position of the rotably driven wheels to be adjustable so that the direction of ball ejection can be varied according to particular practice needs.
With attention now being specifically directed to tennis ball throwing (serving) machines, with which the present invention is principally concerned, one of the problems with known, heretofore available automatic machines is that the ball feeding mechanisms associated therewith have typically been relatively unreliable. Available machines, for example, generally employ an overhead tennis ball hopper located above the ball serving mechanism. Such overhead ball hoppers are generally disc-shaped and are rotatably driven about a vertical axis. A gravity-flow chute is mounted between the hopper and a delivery point at the ball projecting mechanism. Hoppers of this type are constructed having one or more ball-sized openings in the bottom which are positioned for periodic alignment with the chute inlet opening as the hopper is rotated. When these holes are aligned, a ball falls from the hopper into the chute and is conducted thereby to the ball projecting mechanism. The ball feeding rate of such machines is determined by the rotational speed of the hopper and the number of ball feeding holes in the hopper.
A persistent problem associated with feeding tennis balls to a ball throwing or serving mechanism is, however, that the "fuzzy" fabric covering or coating new tennis balls acts somewhat like "VELCRO," thereby tending to make the tennis balls stick together in the hopper and so impending the free falling of the balls when the hopper and chute openings are aligned. As a result, sometimes no balls are fed when they should be and/or balls frequently do not clear the aligned openings before the hopper rotates far enough to catch the ball between structure defining the hopper and chute openings. When this occurs, hopper rotation becomes jammed and ball feeding is interrupted until the trapped ball is manually removed. In addition to being a nuisance to the player being served tennis balls by the machine, undue stresses become applied to the machine, maintenance costs of the machine are increased and excessive wear of the tennis balls may occur. Moreover, the jamming of such types of machines is usually considered unprofessional and tends to downgrade the training facility in the minds of players using the machines. Still further, when individuals are paying by the hour, as is usually the case, for use of the practice machines, they expect the machines to be operating all the time and not to be frequently out of service to clear ball jamming conditions.
Still another disadvantage of such overhead hopper tennis ball throwing machines is that the ball serving mechanisms are generally required to be fairly low to the ground. This causes the tennis balls always to be lobbed upwardly, which is not always the best throwing position insofar as simulation of actual tennis playing is concerned. It is, instead, usually more desirable to have the balls served from a higher elevation to more correctly simulate most playing conditions.
A further problem associated with tennis balls tending to stick to one another is that, depending upon the type of feeding mechanism involved, more than one ball may be fed to the throwing mechanism at the same time or at an unintentionally rapid rate. In such cases when one ball is thrown immediately after another, the second ball may take the individual using the machine by surprise, with the possibility that the individual may be struck and injured by the unexpected second ball or may, at least, undesirably start flinching or tightening up whenever a ball is served towards him or her.
For these and other reasons, improvements are desirable in tennis ball feeding and throwing apparatus to improve the operation of such machines. Therefore, it is a principal objective of the present invention to provide such an improved ball feeding and throwing (serving) apparatus.